1. Field of the Invention
The present invention relates to an ink, an ink cartridge, an ink-jet recording method, and a method for preparing an ink.
2. Description of the Related Art
In recent years, ink-jet recording technologies have been used in a wide range of fields, and an ink usable in various uses has been desired. Pigment inks, in which pigments are used as coloring materials, have been utilized especially in applications where the fastness property is taken very seriously. Regarding an ink-jet recording method, in order to realize a still wider color gamut, so-called special color inks, e.g., red, green, and blue, have become used for pigment inks as well in many cases.
However, the pigments have a specific issue that scattering of light occurs easily because the pigments are present as particles. In particular, in the case where a recording medium is glossy paper, there is an issue that a so-called bronze phenomenon occurs, in which an image recorded on the glossy paper glares in such a manner as metallic luster, or reflected light takes on a color different from the color intrinsic to the pigment depending on the observation angle of the recorded material. This bronze phenomenon is recognized remarkably in an image recorded by a cyan ink. According to the examination of the present inventors, the bronze phenomenon occurs with respect to not only the cyan ink, but also so-called special color inks having hues different from basic colors of subtractive mixture and, therefore, is an issue. Furthermore, this phenomenon becomes especially remarkable when the glossiness of the image is enhanced to improve the image quality. Therefore, it is a large issue to ensure the compatibility between high glossiness and suppression of bronze phenomenon of the image. Here, the bronze phenomenon can be suppressed by reducing the content of the pigment in the ink significantly. On the other hand, the color developability is degraded and, thereby, it becomes difficult to improve the image quality. That is, aspects of the present invention may address an issue to suppress the above-described bronze phenomenon assuming that the color developability of the image is high.
Regarding suppression of the bronze phenomenon of the image, for example, a proposal has been made, in which a polyether modified polysiloxane and a (co)polymer containing a sulfone group are added as a polymer emulsion to an ink (refer to Japanese Patent Laid-Open No. 2003-306620). Furthermore, there is a proposal related to an apparatus in which the bronze phenomenon of an image formed by superposing a plurality of inks can be suppressed through image processing to perform color separation in such a way as to minimize a bronze value (refer to Japanese Patent Laid-Open No. 2008-143135). Meanwhile, regarding enhancement of the color developability of an image, there are proposals related to inks containing a plurality of pigments (refer to PCT Japanese Translation Patent Publication No. 2008-504399 and Japanese Patent Laid-Open No. 2007-314805).